It is commonly known that THC boils at 155 to 157 degrees Celcius. Or, at least, that is a common misconception, since THC actually boils above 400 degrees Celcius. However, vape pens operate at temperatures far below THC’s true boiling point, so how does the cannabinoid turn into an aerosol and get into the lungs?

…THC is transported to your lungs in oil droplets…

Dr. Roggen
Photo courtesy of Mr. Grodski Chemistry.

How do boiling points change?

Water boils at 100 degrees Celsius at normal atmospheric pressure. However, that temperature will change if the pressure changes. This change can be achieved by sucking the air out of a special, sealed chamber with a pump, or much more slightly, with an elevation change.

In fact, it is easier to boil water in a vacuum oven as the pressure can be reduced to near vacuum. At those low pressures water might boil at room temperature. And only at such low pressures is it that THC boils around 155 to 157 degrees Celcius, not at the atmosphere pressure of sea level.

How did THC’s boiling point become so ambiguous?

THC’s boiling point is listed on many chemical references pages, and even Wikipedia, as 155 to 160 degrees Celcius, but that is at 0.05 millimetres in mercury (HG), or close to a full vacuum. Earth’s normal atmosphere at sea level is approximately 760 mm in mercury when looking at a graph in a book, which is one unit of atmosphere, or 101.351 kilopascals (KPA).

So, how do we figure out THC’s actual boiling point from this data if we do not have any other references?

THC only vapes under an adjusted boiling point, otherwise, it turns into an aerosol.
Temperature-pressure nomograph.

What the heck is the Clausius Clapeyron Equation?

A method to figure out THC’s true boiling point is to use a fancy mathematical tool that is designed to adjust boiling points under different pressures. This tool is known as a temperature-pressure nomograph and is based on the Clausius Clapeyron Equation. But, an even easier method to discover THC’s misinterpreted properties is to just call a scientist.

Sometimes it is best to simply #AskAnExpert

I was honestly reminded of THC’s true boiling point while following CBDV on Linkedin, a laboratory in British Columbia, Canada that is licensed by Health Canada to test and research cannabis as well as psilocybin. This lab is now owned by Delic Labs and was founded by Dr. Markus Roggen who holds a Ph.D. in organic chemistry.

CBDV is at the forefront of testing the emissions from vape pens and joints, a test that will become mandatory across the United States by 2022. So, I decided to call Dr. Roggen to learn more about vape pen testing and the state THC is in while it is vaped, especially when considering this remarkably higher boiling point of approximately 425 degrees Celcius.

Dr. Markus Roggen with a THC molecule.

The THC molecule will fall apart before it ever boils in a normal environment. So, how does THC get into the lungs from a vape pen if it doesn’t boil?

For that, we have to mention aerosols. THC does not turn into a gas. The THC is an aerosol phase, so it is in the form of really tiny droplets…

…What it does is, THC droplets are flown into the lungs by the terpenes that turn into gases. So, you turn certain parts of your vape formulation into a gas, and then you also have an airstream that goes through the vape cartridge, capturing small oil droplets… You inhale those oil droplets.

Dr. Roggen

It is known that an additive, propylene glycol, can turn into formaldehyde when it is cooked at a high temperature. However, vape pens can operate at fairly low temperatures, avoiding the production of aldehydes and other toxins from known additives.

The hot air from a joint or vape cartridge is somewhere between forty to sixty degrees Celsius.

Dr. Roggen

Thank you, Dr. Markus Roggen. The phone call will continue in the following series.

In a vape pen, the gasses are the terpenes and the aerosols are the cannabinoids. No cannabinoid boils in the stream of a vape pen, or on the surface of Earth, for that matter.

What about caryophyllene’s boiling point?

Leafly released an infographic on terpenes that displayed caryophyllene’s boiling point as 160 degrees Celcius. (1) However, beta-caryophyllene boils at 168 degrees Celcius at 35 millimetres of Mercury. Furthermore, this author remembers, by memory, that this terpene boils at 129.3 degrees Celcius even closer to a full vacuum.

On the surface of Earth, however, beta-caryophyllene does not boil until approximately 262 to 267 degrees Celsius.

Let us know in the comments if you always knew THC and caryophyllene’s true boiling point. And stay tuned to learn more about vape pen testing in the following installment.

Title photo courtesy of Pixabay. JRByron.

Footnote(s)

https://www.leafly.com/news/cannabis-101/infographic-what-are-cannabis-terpenes-and-how-do-they-affect-you